A primary goal in the harvesting of hay or forage is to dry the hay as soon as possible and then to remove it from direct exposure to sunlight. The hay must be dried before storage to avoid the problems of mold and spontaneous combustion. Exposing the cut hay to sunlight longer than is required to adequately dry it, however, can result in unacceptable loss of nutritive value of the hay due to deterioration of the protein level.
Typically, hay is harvested into approximately five-foot swaths along the ground, and is exposed to sunlight for the initial stage of the drying process. These swaths spread out the hay to maximize exposure to the sun and air to speed initial drying. The swaths of hay are then raked into narrow windrows to remove most of the hay from direct contact with the moist ground. The windrow enhances air circulation within the hay, thereby hastening the drying process. Raking hay into windrows also facilitates gathering of hay by providing rows of forage for a hay baler or other harvesting device to follow.
Many types of wheel rakes have existed for decades. Wheel rakes utilize angled, tined “pinwheels” that are propelled across the ground of a field of cut forage. Contact with the ground while traveling across the ground rotates the wheels and thereby rakes the hay in a desired direction. Of particular interest are V-rakes in which at least two banks of rake wheels are deployed in the shape of a V during operation. Generally, V-rakes employ an arm on each side of a frame to support the wheel rakes. Such V-rakes are used to rake forage into a windrow by raking the forage from the outer edges of the implement inward. V-rakes are preferably adjustable so that the width of the windrow produced is variable and the swath raked on each pass is optimal for the circumstances encountered. For optimal operation, it is preferable that the relative angle of the wheel banks and the width of their separation be independently adjustable.
Wheel rakes are subject to repeated structural stresses due to uneven ground and irregular distribution of forage material when propelled through fields of cut hay to form the hay into windrows. The assemblies supporting the rake wheels must have considerable strength in order to bear such stresses successfully. Welded assemblies are thus preferred for their robustness and durability. In addition, a certain degree of flexibility in motion of the rake wheels is desirable. Some flexibility of the assembly is desired as well.
Wheel rakes convert the forward motion of the rake into a lifting and sideward motion by interaction of the rake wheels with the ground as the wheel rake is drawn forward. Compacted, damp or unusually heavy forage can create problems in that the rake wheels may tend to roll over or skip over areas of heavy compacted forage rather than lifting it and raking it toward the desired windrow. If this occurs, loss of production and increased costs result. Loss of production occurs if forage is left in the fields to decay rather than being harvested. Increased costs can occur if it is necessary to pass through the fields several times to accomplish sufficient raking to gather all of the forage desired.
Rake wheels include a plurality of tines extending from the rim of the wheel. Flexible metal tines lift and move forage to one side as the rake wheels rotate.
Thus, wheel rakes generally have adjustable tension springs that allow the wheels to float. The spring tension can be adjusted to cause more or less of the wheel's weight to bear on the ground. If wheel float is too light, wheels will pass over the crop and leave some of the crop unraked. If wheel float is too heavy, wear on the rake wheels is increased and the rake wheel will dislodge more soil and rocks from the earth and increase contamination of the hay.
Traditionally, and sometimes today, tines extend the entire distance from the rake wheel hub beyond the rim. More commonly tines are attached to the wheel rim and the rim to the hub via spokes or a wheel disk. In the event that spokes are utilized, a plastic disc often covers the spokes. This arrangement keeps forage from passing through the wheel instead of being raked as desired.
Modern rake wheels often utilize metal tines mounted in flexible rubber bases. The rubber bases secure the tines to the wheel rim and provide a measure of controlled flexibility so that each tine can flex in response to loads in all directions without bending or breaking.
Wheel rakes are typically constructed so that multiple rake wheels are mounted side by side mounted on long beams. It is desirable that the beams be adjustable in width or separation and in the angle that the beams make with the path of travel as viewed from above.
Rake wheels are flexibly supported as they pass over the ground so that the full weight of the rake wheel does not rest on the ground. Rake wheel are typically biased upward by springs so that the rake wheels may resiliently flex upwardly as the wheel rake passes over a bump and so that the rake wheels can move downward when the wheel rake passes over a depression in the ground.
Commonly, tension springs are used in cooperation with a bellcrank to resiliently support the rake wheels. The tension springs are generally oriented horizontally while the motion of the rake wheel is along a generally vertical arc. The tension springs are often linked directly to the to the bellcrank or via short chains connected to eyes at the end of the springs. Several problems arise with this arrangement. With repeated stress the spring eyes may suffer metal fatigue and break. This not only interferes with proper raking action but also may cause damage to the rake wheel and cause loss of the spring in the field where it may later cause damage to other farm implements or equipment. For example, a lost spring may interfere with a hay mower during the next mowing of the field and damage the hay mower.
Tension springs may also be damaged by being overextended. If the tension spring is stretched too far it may no longer recoil as it once did. This will cause the rake wheel to bear on the ground to a greater degree than it should and may cause excess wear and or damage.
Further, the tension spring supporting the rake wheel may “snap back” when the spring is loaded and then the load on the tension spring is abruptly released. This can also damage the rake wheel assembly.
Thus the agricultural arts would benefit from a device to provide spring tension for supporting rake wheels and the like that is less prone to breakage and that does not “snap back” when released. It would be beneficial if the device were resistant to overextension as well.